To avoid radio interference by generating a data set expressing the map of signal intensity from the measured signal intensity and information showing the position of the antenna.

Register processing is performed in the manner of transmitting a signal for identifying a mobile telephone (UT) 4a. The transmitted signal is picked up by one satellite or satellites 3a and 3b more than one. On the normal condition, the signal is picked up by the plural satellites 3a and 3b and together with the identifier of UT 4a and the identifiers of satellites 3a and 3b receiving that signal, the intensity or arrival time of received signal is transmitted through a mobile satellite switching center(MSSC) for satellite access nodes(SAN) 1a and 1b under communication with the satellites 3a and 3b to a home position register (HLR) 30. Based on the arrival time of received signal, the HLR 30 calculates the position of UT 4a on the ground. In this case, the data set expressing the map of signal intensity is generated from the measured signal intensity and information showing the position of antenna.